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Discussion Starter · #1 · (Edited)
I've been reading around a few sites regarding how the ECU behaves in the absense of an O2 sensor(s). On 3Si some guys found that by removing atleast one of the primary O2 sensors, the ECU would go get stuck in Open Loop mode with fixed fuel trims. Needless to say this has made tuning with a piggyback much simpler. Does anyone have any more information regarding this sort of behavior?

Thanks.

edit: I should also add that this was in regards to a 1G Fed-spec Stealth. Supposedly the Cali-spec vehicles will reference the other working O2 sensor for Closed Loop operation. Now this makes me wonder if removing both primary O2s will result in limp mode.
 

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I think you could do that but the charaterisits of the "limp mode" probably wouldn't make it very fun to drive, running way rich, retarded timing, etc.

I supposed you could try to tune it back, but it hardly seems simpler than just tuning properly with the piggyback.
 

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Discussion Starter · #3 ·
Chief Brody said:
I think you could do that but the charaterisits of the "limp mode" probably wouldn't make it very fun to drive, running way rich, retarded timing, etc.

I supposed you could try to tune it back, but it hardly seems simpler than just tuning properly with the piggyback.
The limp mode talk was just speculation as to what could happen if both O2 sensors were removed.

I'm interested in disabling closed loop operation.
 

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I think there are even open loop tables based on engine load. The relflash looks awesome.
 

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I been running open loop for a while with my Haltech E8 standalone, ofcourse I use a MAP and IAT Sensor for tuning. But the cars runs really rich, which makes it very impractical for daily driver.
 

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FlashBlueRS said:
With the ECUFlash software, you can force open loop by changing the min coolant temp for closed loop. Change it from 7 to well above normal operating temps and it will never run in closed loop. I don't know if you are able to use it with your ECU though.
Yeah, that is a great global setting. Has anyone messed with the Open Loop maps? I'd figure to maintain closed loop operation up to about 40% load for economy... then open loop can take over.
 

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Discussion Starter · #8 ·
FlashBlueRS said:
With the ECUFlash software, you can force open loop by changing the min coolant temp for closed loop. Change it from 7 to well above normal operating temps and it will never run in closed loop. I don't know if you are able to use it with your ECU though.
That is amazing news. Some of the Galant guys have been talking about swapping out ECUs for the appropriate ones. I might have to go down that path as well.

Clipse3GT said:
I been running open loop for a while with my Haltech E8 standalone, ofcourse I use a MAP and IAT Sensor for tuning. But the cars runs really rich, which makes it very impractical for daily driver.
What are your fuel trims at? With the above mentioned method of removing an o2 sensor, it seems the ECU not only stays in Open-Loop, but also forces all fuel trims to 100%. Are you experiencing something similiar to this?


Thanks a lot for the help.
 
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